01/12/2010 Naive View of Perception Naive View of Perception I - - PDF document

01/12/2010 1

Perception, Causation and the Scientific Study of Human and Machine Consciousness

David Gamez, Imperial College, London

Whitehead Lecture, Goldsmiths, 1st December 2010

Brief Biography

 Background in philosophy  2004-2008, University of Essex. PhD Machine

• consciousness. Worked on EPSRC project to

build a conscious robot.

 2009-2010, Imperial College. Worked with Igor

Aleksander on a new approach for analyzing neural networks for consciousness.

 2010 – present, Imperial College. Working with

Murray Shanahan on a simulator of spiking neural networks. Experimental and analysis work planned for next year.

SpikeStream Talk Overview

 Perception.  Phenomenal and physical.  The science of consciousness.  Hard problem of consciousness.  Causation and consciousness.  Machine consciousness.

PERCEPTION

How can our minds reach out to the objects of experience? What is it about our brains, and their location in the world, that could possibly explain the way consciousness arcs out into the world? Consciousness seems to extend an invisible hand into the world it

• represents. (If I may put it so): how on earth could my

brain make that possible? No ethereal prehensile organ protrudes from my skull! Phenomenologically, we feel that the mind „lays hold‟ of things out there, mentally „grasps‟ them, but we have no physical model of what this might consist in. We flounder in similes. Colin McGinn, The Problem of Consciousness, p. 40

01/12/2010 2 Naive View of Perception

 I directly experience the properties of objects in

the world.

 The properties of objects in the world include

 Colour.  Shape  Weight  Smell  Motion

Naive View of Perception Problems with Naive View

 I can‟t see in the dark.  Covering or damaging my eyes reduces my

ability to see.

 Other people see different things.

Slightly less Naive View of Perception

 The world has the properties that I experience:

 Objects in the world are red.  Objects in the world are round.  Objects in the world are warm.  Objects in the world smell of lavender.

 I experience these properties through signals

from the world.

Slightly Less Naive View of Perception Slightly Less Naive View of Perception

01/12/2010 3

Slightly Less Naive View of Perception

 Science tells us that there is no such thing as

smell or colour in the world.

 Just waves vibrating at different frequencies.  Suggests distinction between primary and

secondary qualities.

Primary and Secondary Qualities

 The world has some of the properties that I

experience (primary qualities):

 Objects in the world are round.  Objects in the world are moving.

 I have ideas of properties that do not exist in the

world (secondary qualities):

 Idea of the smell of a flower.  Idea of red.

 The world has invisible properties / features

 Photons, X-rays etc.  Aromatic molecules.

Primary and Secondary Qualities Primary and Secondary Qualities Projection Theory

 Colours are generated inside our brains.  But we experience colours outside of our heads.  Projection theory: the world that we experience

around us is a combination of real physical

• bjects and a perceptual construction that is

projected out of the brain and spread over the real world.

Primary and Secondary Qualities

01/12/2010 4 Projection Theory The Physical Nature of the Brain Perception of the Body

 Projection theory depends on the idea that our

experience of our heads is in the same location as our physical heads.

 Good reasons for thinking that we do not

directly experience our real physical bodies.

 Will examine:

 Dreams  Phantom limbs  Out of body experiences

Perception of the Body Representation of the Body Projection Theory Interpretation

01/12/2010 5 Dreams Dreams Waking from Dreams Conclusions from Dreams

 Likely that the same thing is going on when we

are dreaming and awake.

 In both cases our phenomenal experiences are

linked to an internal virtual reality model.

 When we are asleep this model can simulate

many different scenarios that do not correspond to the actual environment.

 When we are awake this model is (mostly)

updated using data from the world.

Phantom Limbs

The most extraordinary feature of phantoms is their reality to the amputee. Their vivid sensory qualities and precise location in space – especially at first – make the limbs seem so lifelike that a patient may try to step off a bed

• nto a phantom foot or lift a cup with a phantom
• hand. The phantom, in fact, may seem more

substantial than an actual limb, particularly if it hurts. Ronald Melzack, „Phantom Limbs‟, Scientific America, April 1992, p. 90.

Phantom Limbs

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Projection Theory and Phantom Limbs

Conclusions from Phantom Limbs

 We do not directly experience our real body.  The limbs that we experience before losing a

limb are phantoms.

 Our bodies are phantom bodies.

Out of Body Experiences

Mr Chapple of Halstead, said: “I was in the Exeter hospital ... and was talking to my neighbour when he just collapsed and died. The shock gave me a heart attack, and screens were put around both of our beds. The sister and nurse came to see me, and I was floating in the air above myself, and could see all that was happening – the doctor arrived and spoke to the sister; she went away and brought back an injection, which she gave me. As soon as I received it, I knew no more, and when I awoke next morning, I remembered all that had happened, and the sister confirmed what I had seen. Robert Crookall, Case-Book of Astral Projection, p. 34

Out of Body Experiences Out of Body Experiences Out of Body Experiences

01/12/2010 7 Out of Body Experiences

 Seems highly unlikely that consciousness is

actually projected out of the body during out of body experiences (I am not aware of any strong evidence in favour of this).

 If the brain has a model of the body and its

environment, then it can reposition the body within this environment.

 Just like a virtual reality simulation or a

computer game.

Virtual Reality Model of Perception

 Our conscious experience of the world is linked

to a virtual reality model that is entirely contained within the physical space of each person‟s brain.

 This is the only consistent way of building a

brain-based theory of consciousness

 Pretty weird and spooky – I have argued that

you might want to stop believing in brains if you buy this picture.

Virtual Reality Model of Perception Projection Theory is Wrong! Virtual Reality Model of Perception

 Versions can be found in:

 Kant  Metzinger  Lehar  Dawkins  Revonsuo  Russell  and others ...

Resemblance

 We have no grounds for believing that the

physical world resembles the virtual reality model in any way at all:

 The physical world is colourless.  The physical world is odourless.  The brain has its own representation of space and

time, which may not resemble physical space and time in any way.

 We have no idea what the physical world is like.

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Modern physics, therefore, reduces matter to a set of events which proceed outward from a centre. If there is something further in the centre itself, we cannot know about it ... In places where there are no eyes or ears or brains there are no colours or sounds, but there are events having certain characteristics which lead them to cause colours and sounds in places where there are eyes, ears and brains. We cannot find out what the world looks like from a place where there is nobody, because if we go to look there will be somebody there ... Matter as it appears to common sense, and as it has until recently appeared in physics, must be given up. Bertrand Russell, An Outline of Philosophy, p. 163

Virtual Reality Model of Perception No Resemblance No Resemblance No Resemblance

PHENOMENAL and Physical

01/12/2010 9 Phenomenal and Physical.

 Science of consciousness investigates the

relationship between the physical brain and our phenomenal experiences.

 Phenomenal descriptions and physical

measurements are the data for the science of consciousness.

The Phenomenal World

 The phenomenal world is the totality of our

possible and actual phenomenal experiences - texture, colour, smell, shape, taste, sound and so on.

 Includes phenomenal measurements of the

physical world - the experience of looking at a brain scan or taking a reading from a thermometer.

 We can remember our phenomenal

experiences and imagine them when the corresponding physical objects are not present.

The Physical World

 The physical world is completely non-

phenomenal and never directly appears in the stream of experience.

 Consists of the physical entities that are

deemed by physicists to constitute physical reality - quarks, wave-particles, forces, ten- dimensional superstrings and so on.

 Physical objects are also defined by other

properties, such as spatial extension, mass and velocity, which can be defined mathematically and must be carefully distinguished from their phenomenal representations.

Phenomenal and Physical

 Nothing to do with metaphysical dualism or

substances.

 Two classes of observable phenomena.  Task of the science of consciousness is to

integrate these two sets of observations into a systematic theory.

 A holding back or suspension of judgement

about the „true nature‟ of the phenomenal and physical.

Correlates of Consciousness

 Can look for correlations between the

phenomenal and the physical.

 For example our experience of perceiving a red

flower might be correlated with neurons firing at 40 Hz in a specific region of our brain.

Phenomenal and Physical

01/12/2010 10 Phenomenal and Physical Phenomenal and Physical

SCIENCE of Consciousness

Science of Consciousness

 Start with a system that is known to be

conscious.

 Waking human brain is our current standard

conscious system.

 Artificial systems cannot be used in experiments

• n the correlates of consciousness.

Science of Consciousness

 Measure physical state of waking human brain.  Measure phenomenology using behavioural

reports.

 Systematically vary the waking human brain to

identify correlations between the phenomenal and physical.

From Correlations to a Theory of Consciousness

 When a systematic pattern emerges, a theory of

consciousness can be developed that maps between states of the phenomenal and physical worlds.

 This enables us to make predictions about

phenomenal states on the basis of physical states, and predictions about physical states on the basis of phenomenal states.

01/12/2010 11 Experiment on the Correlates of Consciousness

The Situation of Scientist and Subject

The Science of Consciousness

From Correlates to Falsifiable Predictions

 The study of consciousness will only become a

science when theories are precise enough to make testable predictions.

 Theories that make incorrect predictions will be

discarded.

 Good / strong theories make many falsifiable

predictions.

Formal Theories of Consciousness

 Theories about consciousness are typically

expressed in an imprecise higher level language, for example:

 A phenomenally conscious mental state is a mental

state that either is, or is disposed to be, the object of a higher-order representation.

Formal Theories of Consciousness

 To make predictions about the consciousness it

is necessary to convert the high level language into a formal definition that:

 Specifies the necessary and sufficient conditions for

consciousness.

 Applies to an arbitrary system.  Predict the contents of consciousness.  Could be implemented in computer code.

 Convert philosophical theories of consciousness

into scientific theories of consciousness.

01/12/2010 12 Formal Theories of Consciousness

 Currently only the information integration theory

• f consciousness (Tononi, 2008) can make

detailed predictions about the amount and contents of consciousness in an arbitrary system.

 Work needs to be done on formalizing other

theories of consciousness, such as global workspace theory.

 Artificial systems can be used to explore how

testable predictions about consciousness can be made according to formal theories.

Information Integration

 Information integration theory of consciousness

developed by Tononi (2008).

 Algorithm that analyzes a network of elements

and identifies:

 The elements that are conscious.  The amount of consciousness.  The contents of consciousness.

Conscious Part of the System

Φ=6

Φ=5

Φ=8 Conscious part of the system

Contents of Consciousness EEG Experiments

 Lee et al. (2009) made multi-channel EEG

recordings from eight sites in conscious and unconscious subjects.

 Constructed a covariance matrix of the

recordings on each frequency band, which was used to identify the complexes within the 8 node network using Tononi and Sporns‟ (2003) algorithm.

 Information integration capacity of the network

in the gamma band was significantly higher when subjects were conscious.

TMS / EEG Experiments

 For example, Massimini et al. (2009)  Pulse of TMS applied to different cortical

regions and resulting activity recorded using EEG.

 Activity in cortical areas was more modular and

less differentiated during sleep stages 3 and 4.

 Activity in cortical areas was less modular and

more differentiated during REM sleep and wakefulness.

01/12/2010 13 Problems

 Predicted to take 1010 years to analyze a

system with 30 elements (Aleksander and Gamez, 2010).

 Calibration:

 How much information integration is associated with

how much consciousness?

 What shapes of qualia are associated with which

phenomenal experiences?

 Conceptual issues:

 Representation (Aleksander)  How can the accuracy of different information

integration algorithms be evaluated?

Neurophenomenology

 Emerging discipline that attempts to make

predictions about human phenomenal states on the basis of neural states.

 Typical neurophenomenology experiment:

 Measure brain states using fMRI scanning.  Establish correlations between fMRI patterns and

patterns in the images subjects are viewing.

 Predict the phenomenal states of the subjects when

they are viewing unknown images.

Neurophenomenology

 Currently at an early stage of development.  Have been able to predict:

 Novel images subjects are looking at.  Words subjects are reading.  The task people are intending to perform.  What people are conscious of (as opposed to the

visual stimulus they are exposed to).

 Current work uses statistical properties of the

fMRI data.

 In the future formalized theories of

consciousness could be used.

SpikeStream

HARD Problem

• f Consciousness

Hard Problem of Consciousness

 Hard problem of consciousness tries to explain

how phenomenal experiences arise from physical matter.

 When we think about this problem we typically:

 Imagine (or perceive) a grey brain  Imagine (or perceive) the colour red  Try and fail to imagine how the information-

processing functions of the brain could lead to phenomenal red.

 Arises from confusion between the phenomenal

and physical.

01/12/2010 14 Hard Problem of Consciousness

 The problem with this „problem‟ is that the

physical brain cannot be imagined: it is completely non-phenomenal in character.

 So the hard problem of consciousness can only

be imagined by smuggling in a phenomenal representation, which is then connected to a phenomenal red „quale‟.

 We think we are imagining the physical world.  We are actually imagining phenomenal states

that are correlated with physical representations

• f the physical world.

Hard Problem of Consciousness Third Person Perspective

The Hard and the Real Problems of Consciousness

The Science of Consciousness The Hard and the Real Problems of Consciousness

 The hard problem of consciousness is a pseudo

problem.

 The real problem of consciousness is how the

phenomenal world is connected with the physical world.

 The real problem of consciousness can be

described scientifically and mathematically, but it cannot be imagined in any way.

CAUSATION and Consciousness

01/12/2010 15 Consciousness and Causation

 Experiments on consciousness depend upon a

causal link between consciousness and the reports about conscious states.

 Reports about consciousness must be about

conscious states; they must be caused by conscious states in some way.

Experiment on the Correlates of Consciousness The Science of Consciousness Epiphenomenalism

 Physical world is causally closed.  We experience red, smell of lavender, etc.  The phenomenal world contains information

about the physical world, but does not affect it at all.

Epiphenomenalism Epiphenomenalism

 If there is only a one way link between

consciousness and the physical world, then consciousness cannot be described or spoken about.

 Everything that has been said by physical

human beings about “consciousness” has been caused by physical events in the physical world.

 The word “consciousness” becomes

meaningless

01/12/2010 16 Epiphenomenalism Epiphenomenalism Moving on from Epiphenomenalism

 Epiphenomenalism is philosophical nonsense.  If we want a science of consciousness, we have

to address causal connection between consciousness and the physical world.

 Will look at:

 Physical → physical causation  Phenomenal → phenomenal causation  Physical → phenomenal causation  Phenomenal → physical causation

Physical → Physical Causation

 The physical world is causally closed.  Any event within the physical world can be

completely explained (and possibly predicted) by the set of preceding physical events.

 A conscious event is never needed to explain a

physical event.

Physical → Physical Causation

Phenomenal → Phenomenal Causation

 Phenomenal events can cause other

phenomenal events.

 I imagine eating an apple and then walk down

to the shops to purchase an apple.

 My experience of seeing a red apple causes me

to say “I am having an experience of a red apple.”.

 I also hear myself reporting the phenomenal

states.

01/12/2010 17

Phenomenal → Phenomenal Causation

Physical → Phenomenal Causation

 Physical events can cause phenomenal

sensations.

 Could argue that my brain is causing me to say

that I am conscious of the red apple.

Physical → Phenomenal Causation Phenomenal → Physical Causation

 My report of conscious states has physical

consequences – vibrations in the air, changes

• f brain state of my listeners, etc.

 A science of consciousness must claim that

these physical consequences are caused by the phenomenal states.

Phenomenal → Physical Causation Causal Overdetermination

 The physical world is causally closed.  So the vibrations of the sound waves “I am

conscious of the apple” must have been entirely caused by prior physical events (photons entering the brain, neural processing, etc.).

 The phenomenal world is never needed to

explain the existence of the physical sounds “I am conscious of the apple.”

01/12/2010 18 Causal Overdetermination

 We believe in the phenomenal world and want a

science of consciousness.

 So we also have to interpret the physical sound

vibrations “I am conscious of the apple” as being caused by the phenomenal states.

 The physical sound is caused by preceding

events at both the phenomenal and physical levels.

 It is causally overdetermined.

Causally Overdetermination Causal Overdetermination

 Highly problematic.  Very difficult to see how a science of

consciousness could be constructed without it.

 Not dualism! Dualism rejects causal closure of

physical world.

 Some similarities between causal

• verdetermination and causation between

different levels of description of a physical system.

Crossover Causation Between Levels of Physical Description Crossover Causation Between Levels of Physical Description

MACHINE Consciousness

01/12/2010 19

Strong and Weak Machine Consciousness

 Distinction put forward by Seth (2009).  Strong machine consciousness is the

development of machines that actually are conscious.

 Weak machine consciousness is the use of

machines to model and understand consciousness without any claims being made about the actual consciousness of the machines.

Strong Machine Consciousness

 Work on the waking human brain should

eventually yield an empirically grounded theory

• f consciousness.

 Can use this theory to make predictions about

the actual consciousness of artificial systems.

Strong Machine Consciousness Strong Machine Consciousness

Predictions about Artificial Consciousness

Limitations

 Some potential correlates of consciousness,

such as haemoglobin, cannot be experimentally tested.

 Artificial systems often lack these potential

correlates of consciousness.

 Leads to ambiguity as to whether they are really

phenomenally conscious or not.

01/12/2010 20 Synthetic Phenomenology

 Emerging discipline that studies how we can

make predictions about the phenomenal states

• f artificial systems.

 Ethical implications – answer questions about

whether the robot is suffering.

 Linked up with neurophenomenology.  Can be used to debug cognitive systems that

learn from their experiences.

Experiments

Predicted Distribution of Consciousness According to Tononi’s Theory Predicted Distribution of Consciousness According to Aleksander’s Theory Predicted Distribution of Consciousness According to Metzinger’s Theory

Description of Predicted Phenomenology

01/12/2010 21

CONCLUSIONS

Conclusions

 Virtual reality model of perception  Phenomenal physical distinction and a

correlation-based approach to the scientific study of consciousness.

 Science of consciousness depends on a

problematic causal link between the phenomenal and physical.

 Study and development of machine

consciousness can be grounded in the science

• f consciousness.

Acknowledgements

 Research funded by grants from:

 Engineering and Physical Science Research Council

Adventure Fund (GR/S47946/01)

 The Association for Information Technology Trust.

More Information

 Papers on this material available at:

www.davidgamez.eu/pages/publications/

 SpikeStream: http://spikestream.sf.net.  Feel free to contact me if you have any

questions: david@davidgamez.eu.

 Slides:

www.davidgamez.eu/talks/Gamez_Whitehead2010.pdf

References



Aleksander, I. and Gamez, D. (2010). Informational Theories of Consciousness: A Review and Extension. Proceedings of BICS 2010.



Gamez, D. (2007c). What We Can Never Know. London & New York: Continuum.



Gamez D (2008) The Development and Analysis of Conscious Machines. Unpublished PhD thesis, University of Essex, UK. Available at: http://www.davidgamez.eu/mc-thesis/.



Gamez D (2010) Information Integration Based Predictions about the Conscious States of a Spiking Neural Network. Consciousness and Cognition, 19(1): 294-310.



Lee U, Mashour GA, Kim S, Noh G-J, Choi B-M (2009) Propofol induction reduces the capacity for neural information integration: Implications for the mechanism of consciousness and general anesthesia. Consciousness and Cognition 18(1): 56-64.



Massimini M, Boly M, Casali A, Rosanova M, Tononi G. (2009). A perturbational approach for evaluating the brain‟s capacity for consciousness. Progress in Brain Research, 177:201-214, 2009.



Seth, A.K. (2009). The strength of weak artificial consciousness. International Journal of Machine Consciousness. 1(1):71-82.



Tononi G (2008) Consciousness and Integrated Information: a Provisional

• Manifesto. Biol. Bull. 215: 216–242.



Tononi G and Sporns O (2003) Measuring information integration. BMC Neuroscience 4:31.